Before a company can pay a new vendor, especially one likely to be 1099-reportable, it needs a completed W-9 on file: the vendor's legal name, business type (individual, corporation, partnership), address, and taxpayer identification number. This becomes the vendor's official tax record for reporting purposes.

Missing or incomplete W-9 information at onboarding is a common source of downstream problems: incorrect 1099 filings, IRS backup withholding requirements, and delayed payments while someone chases the vendor for the missing document.

Frequently Asked Questions

When does a company need to collect a W-9?

Before making the first payment to a new US vendor or contractor, so the taxpayer information is already on file well before a 1099 filing deadline requires it, rather than being chased down after the fact at year-end.

What happens if a vendor doesn't provide a W-9?

The paying business may be required to apply backup withholding, holding back a percentage of the payment and remitting it to the IRS directly, until proper taxpayer information is provided.

How does a W-9 differ from a W-4?

A W-4 is completed by employees for payroll tax withholding. A W-9 is for non-employees, contractors and vendors, whose payments are reported differently and aren't subject to standard payroll withholding.

How does an AI agent handle W-9 collection during vendor onboarding?

It can request the document, validate that it's complete and the taxpayer ID format is plausible, and flag missing or inconsistent information for follow-up, rather than a vendor's first payment being held up by a form nobody realized was missing.